The present disclosure relates to a cell sorting apparatus for sorting target cells, a cell sorting chip implementing the apparatus and a cell sorting method for the apparatus.
As apparatus for sorting cells, a fluorescent flow cytometer and a cell sorter are known. In these apparatus for sorting cells, the cells are kept on an air-liquid interface at a spout by surrounding fluid under proper vibration conditions generally including an exit flowing velocity of several m/s and a vibration frequency of several tens of kHz. At the same time, electric charge is also given to the cells. The cells each fly as a liquid drop in air, to which a static electric field is applied, in a direction according to the amount of the electric charge given thereto. Finally, the cells are sorted in a cell sorting container provided outside the flow channel.
For relatively high flowing velocities such as the one cited above, this technology is useful. In a flow cytometer with relatively low flowing velocities or a dielectric cytometer, however, it is difficult to satisfy a liquid-drop conversion condition and a discharging condition. Thus, it is desirable to rather provide a configuration in which a sorting operation is carried out on cells in a flow channel including branch flow channels and, at a later stage, the cells are held.
As a cell sorting mechanism in a flow channel, there has been proposed a method in accordance with which, for example, a piezo device or the like is used for changing the flowing direction of fluid in order to indirectly driving cells included in the fluid. However, the responsiveness of this mechanical device has a value in the order of about several milliseconds. Thus, if the responsiveness of a pressure wave in the flow channel is taken into consideration, this cell sorting mechanism provides a limited cell sorting speed.
As a method for directly driving cells, on the other hand, there has been proposed a dielectrophoretic-force method. A typical document such as JP-T-2003-507739 (refer to, among others, FIGS. 1 and 2) (hereinafter referred to as Patent Document 1) discloses the dielectrophoretic-force method in accordance with which a difference in dielectrophoretic force between cells flowing through a flow channel provided with embedded electrodes and a difference in sinking velocity between the cells are used to sort the cells into a plurality of cell groups having cell types different from each other.